This invention pertains to the art of solvent
blends and solvent/resin blends. More, particularly this invention pertains to blends that do not contribute to the formation of ground based ozone or smog. The invention is particularly applicable to solvent blends and solvent/resin blends that have no volatile organic compounds for use with adhesives, coatings, inks, cleaning and blowing agents and the like and will be described with particular reference thereto. However, it will be appreciated that the invention may be advantageously employed in other environments and applications.
Heretofore, hydrocarbon-based solvents have been used to dissolve organic materials in many industrial applications. However, recently, hydrocarbon-based solvents have fallen out of favor because they have been classified by the United States Environmental Protection Agency and other international regulatory bodies as materials that contribute to the formation of ground based ozone or smog. This has created a need for other types of solvents for the production of coatings, adhesives, inks and the like.
Upon evaporation, a highly-reactive, hydrocarbon-based solvent reacts with hydroxyl radicals and ultraviolet light very close to the ground to form a photochemical smog that is considered harmful and in some cases dangerous. Some cities have severe smog which reduces visibility and actually causes "ozone alerts". In part, the smog is caused by hydrocarbon emissions from cars. However, another major contributor is industrial use of hydrocarbon-based solvents such as hexane and toluene.
The benchmark for desired reaction rates of hydrocarbon-based compounds is ethane. If a compound has a reaction rate with the hydroxyl radical and ultraviolet ("UV") light that is faster than ethane, the compound reacts too close to the ground and consequently generates ozone and smog. Such compounds are defined as volatile organic compounds (VOCs). On the other hand, if a compound has a reaction rate that is slower than ethane, the compound reaches higher into the atmosphere before reacting with the hydroxyl radical and UV light. In such instances the non-VOC compound does not contribute to the formation of ground based ozone and smog.
Some of the more reactive VOCs are:
toluene; PA1 methyl ethyl ketone; PA1 diacetone alcohol; PA1 hexane; PA1 isopropyl alcohol; PA1 pentane; PA1 dibasic esters; PA1 trichloroethylene; PA1 benzene; PA1 ethyl acetate; PA1 butyl acetate; PA1 n-methyl pyrollidone; PA1 glycol ethers; PA1 d-limonene; PA1 terpene hydrocarbon solvents; PA1 dimethyl ether; and, PA1 tetrahydrofuran. PA1 chlorobromomethane; PA1 1-bromopropane; PA1 n-alkane (C12-C18); PA1 t-butyl acetate; PA1 perchloroethylene; PA1 benzotrifluoride; PA1 parachlorobenzotrifluoride; PA1 acetone; PA1 1,2-dichloro-1,1,2-trifluoroethane; PA1 dimethoxymethane; PA1 1,1,1,2,2,3,3,4,4-nonafluoro-4-methoxy-butane; PA1 2-(difluoromethoxymethyl)-1,1,1,2,3,3,3-heptafluoropropane; PA1 1-ethoxy-1,1,2,2,3,3,4,4,4-nonafluorobutane; and, PA1 2-(ethoxydifluoromethyl)-1,1,1,2,3,3,3-heptafluoropropane. PA1 a) acrylic-thermoplastic; PA1 b) acrylic-thermosetting; PA1 c) chlorinated rubber; PA1 d) epoxy (either one or two part); PA1 e) hydrocarbon (e.g., olefins, terpene resins, rosin esters, coumarone-indene, styrene-butadiene, styrene, methyl-styrene, vinyl-toluene, nitrocellulose, polychloroprene, polyamide, polyvinyl chloride and isobutylene); PA1 f) phenolic; PA1 g) polyester and alkyd; PA1 h) polyurethane; PA1 i) silicone; PA1 j) urea; and, PA1 k) vinyl and vinyl acetate. PA1 1) chlorobromomethane; PA1 2) 1-bromopropane; PA1 3) methyl acetate; PA1 4) n-alkane (C12-C18); PA1 5) t-butyl acetate; PA1 6) perchloroethylene; PA1 7) benzotrifluoride; PA1 8) parachlorobenzotrifluoride PA1 9) acetone; PA1 10) 1,2-dichloro-1,1,2-trifluoroethane PA1 11) dimethoxymethane; PA1 12) 1,1,1,2,2,3,3,4,4-nonafluoro-4-methoxy-butane; PA1 13) 2-(difluoromethoxymethyl)-1,1,1,2,3,3,3-heptafluoropropane; PA1 14) 1-ethoxy-1,1,2,2,3,3,4,4,4-nonafluorobutane; PA1 15) 2-(ethoxydifluoromethyl)-1,1,1,2,3,3,3-heptafluoropropane; PA1 16) methylene chloride; and, PA1 17) technical white oils (mineral oils). PA1 1a) adhesives PA1 2a) blowing agents PA1 3a) coatings PA1 4a) cleaning compositions PA1 5a) inks
Governmental regulations limit the use of VOCs in coatings, inks, and adhesives. As a result, water-borne coatings have become the most important type of coatings in coating and adhesive systems. However, water-borne coatings must contain some volatile organic compound content. This is because water flashes off too fast from the water-based latex or emulsion to make a good film. To alleviate this problem, 7-10% of a slower evaporating solvent such as a glycol ether is added to the latex to aid in film formation. Unfortunately, glycol ethers are primary examples of VOCs and thus dangerous to the environment.
Halogenated hydrocarbon-based compounds have reaction rates that are slower than ethane. However, these halogenated compounds are ozone depleting. consequently, they are not suitable VOC-free solvents.
In the prior art, U.S. Pat. No. 5,102,563 to Desbiendras describes a solvent composition which contains methyl tert butyl ether. However, methyl tert butyl ether is a VOC and thus unsafe for the environment. Similarly, U.S. Pat. No. 4,898,893 to Ashida describes a composition for making a blowing agent which contains a flammable aliphatic hydrocarbon. This is also a VOC. U.S. Pat. No. 3,950,185 to Toyama teaches film removing compositions which contain methylene chloride and bromochloromethane which are not VOCs. However, these compositions also contain methanol and monochlorobenzene which are VOCs. U.S. Pat. No. 3,924,455 to Begishagen describes a formulation containing mineral spirits which removes lacquer stress coatings. These mineral spirits are also VOCs.
An object of the present invention is the identification of some high-performance solvents and solvent/resin blends which are non-flammable or self-extinguishing and do not contribute to the formation of ground-based ozone.
Another object of the present invention are solvents and solvent/resin blends that are safer to the environment than even water-based systems which still must contain a volatile organic solvent to aid in film formation.
Yet another object of the present invention are environmentally-safer solvent compositions which do not contribute to the formation of ground based ozone which will be useful in the formulation of cleaning agents, coatings, adhesives, inks and also blowing agents for the production of plastic foams.